Brain organization and habitat complexity in Anolis lizards

Area of Science:

• Comparative neuroanatomy
• Ecology
• Evolutionary biology

Background:

• A broad correlation exists between vertebrate neuroanatomy and preferred habitat complexity.
• Species in more complex habitats generally exhibit larger brains and specialized structures for navigation and exploitation.

Purpose of the Study:

• To empirically measure structural habitat complexity and neuroanatomy in Puerto Rican Anolis lizards.
• To test the hypothesis that habitat complexity drives neuroanatomical divergence in Anolis lizards.

Main Methods:

• Quantified structural habitat complexity for six Anolis lizard species.
• Measured whole brain volume and six specific brain structures potentially related to complex habitat exploitation.
• Analyzed interspecific variation in habitat complexity and neuroanatomy.

Main Results:

• Significant interspecific variation in structural habitat complexity was observed, even within the same ecomorph category.
• No evidence supported the hypothesis that habitat complexity differences drive neuroanatomical divergence.
• Species within the same ecomorph category showed considerable variation in microhabitat preferences.

Conclusions:

• Habitat complexity alone may not be sufficient to drive divergent brain evolution in arboreal species.
• Fine-scale habitat partitioning allows sympatric Anolis species of the same ecomorph to coexist.
• Interspecific variation in microhabitat selection plays a role in Anolis community structure.